1. Field of the Invention
The present invention relates to an improvement in waveguide fabrication, and relates more particularly to an improved method of connecting end to end placed tubular members as well as improvements in connecting a waveguide tubular member perpendicularly to an end flange.
High power multi-carrier microwave space antenna waveguides are important to the communication capability of a satellite which is oribiting the earth. Conventional waveguides are hollow tubes made preferably from a graphite composite and are subsequently metal plated to effect electrical conductivity. Usually the plating used is copper or silver.
The process of launching satellites into space involves a very weight conscious process. It has been calculated that the cost for launching a pound of payload material into space is on the order of many thousands of dollars. Therefore, it is incumbent upon satellite manufacturers to use materials which are light weight, yet function with equal effectiveness as conventional metals such as aluminum. Thus, the use of graphite composite or other composite materials in the fabrication of waveguides has evolved as a standard practice. However, the fabrication of joints using composite materials which require exacting standards is problematic given that processes, such as, milling or machining, are not usually part of composite joint construction.
Accordingly, it is an object of the present invention to provide a method and tool for aligning tubular members used as waveguides in a satellite and connecting same with exacting tolerance.
It is a further object of the invention to provide a method for connecting the end of a tubular waveguide to a waveguide mounting flange at a perpendicular angle with repeatable accuracy.
A further object of the invention is to provide a continuous free path of conduction within the metal plated waveguide that does not allow RF energy within the waveguide to leak out.
Still a further object of the invention is to provide a method and apparatus which overcomes edge effects at waveguide ends due to bowing of the walls by keeping the cross section of the tubular members at the required dimensions during bonding.
Still a further object of the invention is to provide a tool which is readily removable and requires minimum work once bonding is complete for removal.
Yet still a further object of the invention is to keep excess adhesive on the inside of the waveguide contained close to the inner wall in the embodiment of the butt joint connection.
Still a further object of the invention is to provide tooling which is extracted from the waveguides using readily available means such as string.
Still yet a further object of the invention is to overcome the other problems known with edge effects at waveguide ends by keeping the cross section of the tubular members at required dimensions during bonding.
The invention resides in a method of connecting two tubular members in an end to end manner each having an internal confine extending in a longitudinal direction, wherein the method comprises the steps of: providing a tool correspondingly sized and shaped to fit within the hollow tubular confine of each of the tubular members; positioning the tool between the opposed ends of each tubular member such that a portion of the tool extends into one tubular member and portion of the tool extends into the other tubular member thereby bridging the two tubular members; applying adhesive and an exterior strap or straps between the opposed ends of each of the one and another tubular members and the tool, and constructing the tool from a material which does not adhere, or covering the tool with a material which does not adhere, to the adhesive used in forming the joint.
Ideally, the step of positioning the tool between the opposed ends of the tubular members further includes the step of first positioning the tool within one end of the one tubular member such that a portion of the tool extends outwardly therefrom and telescoping the other of the tubular members over the portion of the tool extending outwardly from the one tubular member and abutting the juxtaposed edges of the ends of the tubular members with one another.
Desirably, the tool is provided as a plurality of interconnected parts to make up a rectangular solid by providing each of the plurality of interconnected parts with longitudinally extending mating members which ate correspondingly sized and shaped to fit within corresponding members formed on the part to which one part is connected.
The step of providing the tool as a plurality of interconnected parts includes the step of connecting each of the plurality of parts making up the tool with a string or other connecting device and connecting at least two of the plurality of parts with the string in opposite directions within each of the tubular members and waiting for the adhesive to cure and thereafter pulling each of the strings apart from the outside end of the members to disassemble the tool from the connection joint.
The invention also relates to an apparatus having a central axis for aligning and butt connecting two tubular members to one another and comprises a plurality of parts each of the parts having one side edge and another side edge; the one side edge of one of the parts and the other side edge of the other of the parts having corresponding shaped portions which interfit and correspond to the height or width of the tubular member and are laterally slidable relative to one another such that when the one side edge and the other side edge of the parts are placed together the tool has a closed shape; and wherein the correspondingly shaped portions of the parts of the apparatus extend parallel to the central axis of the tool such that the parts slide relative to one another axially.
The invention further resides in a method of mounting and bonding a flange to a tubular member comprising the steps of: providing a tool having a base plate having an accurately formed top surface and a central point thereon; providing an insert correspondingly sized and shaped to be closely received within the inner confine of the tubular member; securing the flange to the base plate at a predetermined location relative to the central point thereon; providing the flange such that it has an inner surface which comes into contact with the tubular member outer surface; locating the insert within the tubular member and securing the insert to the base plate relative to the central point and applying adhesive between the flange inner surface and the tubular member outer surface in order to bond the surfaces together.
The invention also resides in an apparatus for locating a flange on a tubular member comprising: a base plate having a center; a plurality of primary holes formed geometrically about the center; the base plate having a plurality of secondary holes formed radially outwardly of the center beyond the primary holes; the secondary holes corresponding to the position of holes in a flange to be connected to a tubular member; an insert having a shape corresponding in size and shape to that of the interior surface of the tubular member; and the insert being located by some means (e.g. a hole) such that the central axis of the insert corresponds to the central point on the base plate.